Multi-phase switching converters present a number of advantages over single phase switching converters. In particular, multi-phase switching converters exhibit greater efficiency than single-phase switching converters for large load currents. For small load currents, efficiency can be improved by operating the multi-phase switching converter in a single-phase mode of operation.
Upon switching between multi-phase and single-phase modes, the switching converter can exhibit a poor transient response resulting in undershoot or overshoot of the output voltage.
Such overshoots and undershoots may be reduced by implementing adaptive voltage positioning AVP control techniques. When using AVP control, the output voltage can vary between a minimum value and a maximum value and can remain at or close to these values. The AVP resistance, RAVP, is expressed as the ratio of the change in output voltage over the change in load current. The AVP resistance can be set to a specific value depending on a specific application.
When RAVP is changed, a current value at which phase circuits of the multi-phase switching converter are enabled or disabled also changes. This reduces the efficiency of the multi-phase switching converter.